<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="./css/index.css" />
</head>
<body>
  <!-- 主体区域 -->
  <section id="app">
    <!-- 输入框 -->
    <header class="header">
      <h1>小黑记事本</h1>
      <!-- 
        添加功能:
          1.通过v-model绑定输入框 -> 实时获取表单元素的内容
          2.点击按钮,进行新增,往数组最前面加 unshift
      -->
      <input v-model="todoName" placeholder="请输入任务" class="new-todo" />
      <button @click="add" class="add">添加任务</button>
    </header>
    <!-- 列表区域 -->
    <section class="main">
      <ul class="todo-list">
        <li class="todo" v-for="(item, index) in list" :key="item.id">
          <div class="view">
            <span class="index">{{ index + 1 }}</span> <label>{{ item.name }}</label>
            <button class="destroy" @click="destroy(item.id)"></button>
          </div>
        </li>
      </ul>
    </section>
    <!-- 统计和清空 -->
    <footer v-show="list.length > 0" class="footer">
      <!-- 统计 -->
      <span class="todo-count">合 计:<strong>{{ list.length }}</strong></span>
      <!-- 清空 -->
      <button class="clear-completed" @click="clear">
        清空任务
      </button>
    </footer>
  </section>
  
  <script src="https://cdn.jsdelivr.net/npm/vue@2.7.16/dist/vue.js"></script>
  <script>
    new Vue({
      el: '#app',
      data: {
        todoName: '',
        list: [
          { id: 1, name: '跑步一公里' },
          { id: 2, name: '跳绳200次' },
          { id: 3, name: '游泳100次' },
        ]
      },
      methods: {
        destroy(id) {
          this.list = this.list.filter(item => item.id !== id)
        },
        clear() {
          this.list = []
        },
        add() {
          if (this.todoName.trim() === '') {
            alert('请输入任务名称')
            return
          }
          // unshift  往数组最前面添加数据
          this.list.unshift({
            id: +new Date(),
            name: this.todoName
          })
          this.todoName = ''
        }
      }
    })
  </script>
</body>
</html>